Read it through once

The Thirty Mile River was wide open. Its wild water defied the frost, and it was in the eddies only and in the quiet places that the ice held at all. Six days of exhausting toil were required to cover those thirty terrible miles. And terrible they were, for every foot of them was accomplished at the risk of life to dog and man. A dozen times, Perrault, nosing the way broke through the ice bridges, being saved by the long pole he carried, which he so held that it fell each time across the hole made by his body. But a cold snap was on, the thermometer registering fifty below zero, and each time he broke through he was compelled for very life to build a fire and dry his garments.